Vehicle application system development consists of design, development, confirmation using vehicle CAN (Controller Area Network) signal. As to do this kind of process, very high costs and much time are required, further high risk is included. So, developers have designed and used simulation environment. But, vehicle application system developers are asking for methods of cost saving, few risks, and cut to development period. This paper introduces method of simulator design for vehicle application system development based on GMLAN (General Motor Local Area Network).